What you're describing is just xenophobia, and that certainly a problem with some people, but not everyone, especially not in areas that have high enough demand

What you're describing is just xenophobia, and that certainly a problem with some people, but not everyone, especially not in areas that have high enough demand for specialized stores. Making distinction of different cuisines is not that. "American grocery stores" also cater to the demographics around them. For example, Safeways in the Bay Area carry all the staples necessary to make Mexican food despite being an "American" grocery store.